Jesus gave that warning because He knew that many would come in His name, claiming to be Christ, as thye surely have, but Baha'u'llah never claimed to be Christ, He came with a New Name...
Also, just because there have been false prophets that does not mean there would not be any true prophets, and that is basic logic. If there were never going to be any true prophets, why would Jesus have said the following?
Matthew 7:15-20 Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves. Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles? Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit. A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit. Every tree that bringeth not forth good fruit is hewn down, and cast into the fire. Wherefore by their fruits ye shall know them.
You are always bringing out little technicalities, like when Christians say that Jesus will return and then you point out that Jesus never said he was going to return". It was usually worded that when the "Son of Man" returns or something similar. But, this time, you are the one adding Jesus and Christ into the mix when the verse you use doesn't say Jesus or Christ, it says "false" prophets in sheep's clothing.
Although, earlier in Matthew it says...
3 “Tell us,” they said, “when will this happen, and what will be the sign of your coming and of the end of the age?”
4 Jesus answered: “Watch out that no one deceives you. 5 For many will come in my name, claiming, ‘I am the Messiah,’ and will deceive many. 6 You will hear of wars and rumors of wars, but see to it that you are not alarmed. Such things must happen, but the end is still to come. 7 Nation will rise against nation, and kingdom against kingdom. There will be famines and earthquakes in various places. 8 All these are the beginning of birth pains...
21 For then there will be great distress, unequaled from the beginning of the world until now—and never to be equaled again.
22 “If those days had not been cut short, no one would survive, but for the sake of the elect those days will be shortened. 23 At that time if anyone says to you, ‘Look, here is the Messiah!’ or, ‘There he is!’ do not believe it. 24 For false messiahs and false prophets will appear and perform great signs and wonders to deceive, if possible, even the elect. 25 See, I have told you ahead of time.
26 “So if anyone tells you, ‘There he is, out in the wilderness,’ do not go out; or, ‘Here he is, in the inner rooms,’ do not believe it. 27 For as lightning that comes from the east is visible even in the west, so will be the coming of the Son of Man.
So who do Baha'is see as being these false messiahs and false prophets? And you know that I always point out that to not be deceived one thing a person needs to look out for is that there will be wars and rumors of wars etc.... but that is not yet the end? That if those days weren't cut short no one would survive? I don't see how Baha'is can say those things have already happened. But, it sure seems like we are heading towards those kinds of catastrophic events. So has the true Messiah already come? Baha'is say "yes, he has." And that he predicted that his message would be rejected and that the world would then go through all kinds a tribulations. And things would get so bad that the only way out of it would be to turn to the Baha'i Faith.
So what kinds of disasters have the Baha'i leaders predicted? The World Wars? I think they did. Nuclear bombs? I think they predicted that too. Weren't Baha'is warned to get out of the cities? That America would "burn" because of their racial problems? Were the Baha'is warned to get out of Iran? What do Baha'is say to do about climate change and other problems we are facing right now?
Next problem. It gets so bad that we turn to the Baha'is. Then what? Do we say, "Okay LSA of San Francisco, what do we do? Can you fix this mess? Do you want to take over the governing of the city?" What about the county and state governments? What do Baha'i teachings want them to do? Then the NSA of the United States. The U.S. government says, "Here, we give up. You take over and fix this.? Then the UHJ, "Okay, you're in control. Tell all the nations to work together and stop fighting."
What's the Baha'i plan? If the world turns to the Baha'is, are they ready to take over and put "God's" laws and "God's" government into action? Or, as things are crumbling do Baha'is just sit by? Because, things are crumbling and too many Baha'is seem to be just sitting by. What are they supposed to be doing to get ready for when the %&#* hits the fan? But still, that's just the birth pangs and are not yet the end? Baha'u'llah, the end-time Messiah, has come and gone and we are still going through the birth pangs?